Export Foursquare checkins to GPX

main.swift

//
//  main.swift
//  ForsquareGPX
//
//  Created by Dzianis Lebedzeu on 07/06/2015.
//  Copyright (c) 2015 Home. All rights reserved.
//

import Foundation

let token = "YOUR_FORSQUARE_TOKEN"

var checkins = [NSDictionary]()
let limit = 250

func iso8601Formatter() -> NSDateFormatter {
    let formatter = NSDateFormatter()
    formatter.locale = NSLocale(localeIdentifier: "en_US_POSIX")
    formatter.dateFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'Z'"
    
    return formatter
}

func escapeXML(xml: String) -> String {
    return CFXMLCreateStringByEscapingEntities(kCFAllocatorDefault, xml, nil) as String
}

func checkinsURLWithOffset(offset: Int) -> NSURL {
    let path = "https://api.foursquare.com/v2/users/self/checkins"

    let urlComponents = NSURLComponents(string: path)!
    
    let dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = "YYYYMMDD"
    
    urlComponents.queryItems = [
        NSURLQueryItem(name: "oauth_token", value: token),
        NSURLQueryItem(name: "v", value: dateFormatter.stringFromDate(NSDate())),
        NSURLQueryItem(name: "limit", value: "\(limit)"),
        NSURLQueryItem(name: "offset", value: "\(offset)")]
    
    return urlComponents.URL!
}

func fetchCheckins(offset: Int) {
    println("fetching checkins with offset: \(offset)")
    
    let task = NSURLSession.sharedSession().dataTaskWithURL(checkinsURLWithOffset(offset)) { (data, urlResponse, error) -> Void in
        if let error = error {
            println(error.localizedDescription)
            exit(1)
        }
        
        var jsonError: NSError?
        let json = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.allZeros, error: &jsonError) as? NSDictionary
        
        if let json = json {
            if let serverError = json.valueForKeyPath("meta.errorDetail") as?  String {
                println(serverError)
                return
            }
            
            let items = json.valueForKeyPath("response.checkins.items") as? [NSDictionary]
            let count = json.valueForKeyPath("response.checkins.count") as? Int
            if let items = items, count = count {
                if (offset < count) {
                    checkins += items
                    fetchCheckins(offset + limit)
                } else {
                    writeCheckinsToGPX(checkins)
                }
            }
            
        } else if let jsonError = jsonError {
            println(jsonError.localizedDescription)
            exit(1)
        }
        
    }
    
    task.resume()
}

func writeCheckinsToGPX(checkins: [NSDictionary]) {
    
    let formatter = iso8601Formatter()
    let now = formatter.stringFromDate(NSDate())
    
    var xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?>\n" +
    "<gpx xmlns=\"http://www.topografix.com/GPX/1/1\" xmlns:gpxx=\"http://www.garmin.com/xmlschemas/GpxExtensions/v3\" xmlns:gpxtpx=\"http://www.garmin.com/xmlschemas/TrackPointExtension/v1\" creator=\"Oregon 400t\" version=\"1.1\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd\">\n" +
        "<metadata>" +
        "<link href=\"http://www.foursquare.com\">" +
        "<text>Foursquare Checkins</text>" +
        "</link>" +
        "<time>\(now)</time>" +
        "</metadata>" + "\n"
    
    for checkin in checkins {
        if let name = checkin.valueForKeyPath("venue.name") as? String,
            let lat = checkin.valueForKeyPath("venue.location.lat") as? Double,
            let lon = checkin.valueForKeyPath("venue.location.lng") as? Double, 
            let time = checkin.valueForKeyPath("createdAt") as? Double {
            let date = NSDate(timeIntervalSince1970: time)
                
            xml += "\n<trk><name>\(escapeXML(name))</name><trkseg><trkpt lat=\"\(lat)\" lon=\"\(lon)\"><time>\(formatter.stringFromDate(date))</time></trkpt></trkseg></trk>"
        }
    }

    xml += "\n"
    xml += "</gpx>"
    
    println("writing data to GPX file...")
    
    var error: NSError?

    xml.writeToFile("foursquare.gpx", atomically: true, encoding: NSUTF8StringEncoding, error: &error)
    assert( error == nil, "Failed to write GPX.")
    
    println("Done.")
    exit(0)
}

fetchCheckins(0)
dispatch_main() // TODO: Any better solutions for async console execution?